The present invention relates generally to a method and apparatus for mounting an optical lens in an optical device and, more particularly, relates to a method and apparatus for mounting a liquid lens.
In many instances, optical devices will be provided with a fixed focal length lens. For example, some cameras have only a fixed lens, which can be mounted to the camera body through the use of a bonding material, such as glue. FIG. 1 illustrates such a structure and a method by which a fixed focal length lens is typically mounted to the camera. The camera C is typically provided with a integral sleeve S with an inside diameter sized to receive a standard lens barrel. A lens L having that diameter is positioned in the sleeve, after which a cylindrical bead of glue G is placed inside a recessed channel on the interior surface of sleeve S, in contact with the sleeve and the lens L. Typically, UV (ultra violet) glue is utilized. Such glue needs to be exposed to ultra violet light in order to set and form a bond. It is typical to provide such ultra violet radiation U through a barrel B which is made of a material that can conduct the radiation directly to the joint from the end of the barrel. After a predetermined period of radiation, the bond is completed. This is a particularly effective process which may be used for manufacture, for example, on a production line.
Liquid lenses are becoming increasingly popular. They are a form of lens in which the focal length is varied electronically, requiring no moving parts within the lens and no complicated, multiple lens structures. Moreover, they are roughly the same size as a fixed focal length lens and are available with the same lens barrel diameters. They therefore offer an excellent choice to provide a variable focal length lens in existing cameras, or existing cameras can be readily retrofitted so as to have a variable focal length lens.
One problem presented by the use of liquid lenses is that, although they can be provided in a barrel and general size equal to a fixed focal length lens, the front portions must be of a somewhat larger diameter (see lens 10 in FIG. 2). Thus the ultraviolet radiation transmitted from the end of barrel B in FIG. 1 would be blocked by the front portion of the lens. On the other hand, if the diameter of barrel B were made large enough to clear the front portion of the lens 10, ultraviolet light emitted from the end of the barrel B would be far away from the glue G and will not be able to cure it.
Basically, it is an object of the present invention to mount a liquid lens in an existing optical instrument opening dimensioned for a fixed focal length lens utilizing an existing bonding material which is cured by light.
Moreover, it is an object of the present invention to mount a liquid lens in an existing camera opening without compromising the strength of the mounting and to do so in a manner which is reliable and convenient in use, yet relatively inexpensive.